Fruits, berries, and other agricultural commodities which are packed while moist are susceptible to premature spoilage Accordingly, it is necessary to avoid picking berries or similar commodities while wet, or to dry the commodities before they are packed. For example, if blueberries are subjected to continuous rainfall during the time for picking, these berries normally could not be picked and fresh-packed.
Blueberries are delicate and must be handled carefully and dried quickly to prevent bruising and spoilage. Heat should not be used in the drying process, as it hastens the deterioration of the berries.
Apparatus for drying berries and other fruits is known in the art. One such example is shown in U.S. Pat. No. 1,912,419, which discloses a dryer having a rotary drum mounted for rotation on a horizontal axis. A helical track mounted on the inner surface of the drum moves the fruit through the drum as the drum rotates. A moving stream of air and absorbent material on the inner surface of the drum dry the fruit. U.S. Pat. No. 565,522 discloses a drum dryer for flour or grain including an open-ended perforated outer cylinder and a fan mounted in the end of the drum to draw air through the drum. The drying action of these dryers is relatively slow, notwithstanding the perforated drying drums used therein.